Communities & Environment > Planning > Housing > Accessory Dwelling Units

Accessory Dwelling Units

In 2016 California adopted new laws intended to make it easier for property owners to create Accessory Dwelling Units (ADUs), also known as second units, granny flats, or in-law units. ADUs are dwellings that exist on a lot with another house, and can be either attached or detached from the main house. The new laws limit the ability of local governments to regulate ADUs and mandate that all local agencies adopt an ADU ordinance that is consistent with the new requirements by January 1, 2017. If a local jurisdiction fails to adopt an ordinance, the state legislation will preside.

California Department of Housing and Community Development (HCD) staff has issued a technical assistance booklet.

The League of Cities will also be developing a guidance memo, expected in April.

Additional background materials are available below:

From 21 Elements (additional materials available at


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